PTO on a TC40

cvpuser · Jun 6, 2004

Hi gang.

I have a TC40 and am pulling a 72" Woods Bush Bull rotory cutter. It's been working great for two years, but last night the drive shaft to the cutter started slowing down when I got into medium/tall grass -- that's never happened before.

I thought at first that the clutch on the cutter may be slipping and began looking for the instructions to adjust it. However, the more I thought about it, I began to wonder if the drive shaft would slow down if the clutch was slipping /forums/images/graemlins/confused.gif. If it was the clutch, wouldn't the shaft continue to turn at high speed and the mower would slow down?

So, now I'm wondering if my PTO is slipping somehow.

Anyone have thoughts on what might be wrong? If it is the clutch on the cutter, does anyone know how to adjust it?

Thanks
Wally

Glenn9643 · Jun 6, 2004

If the slippage is in the clutch on your PTO shaft, the PTO section from the tractor to the slip-clutch will continue to turn at normal speeds and the section of the slip-clutch directly connected to the cutter gearbox will slow down. If the pto shaft from the tractor slows down and the engine is lugged down from the load you need to slow your ground speed and see if that helps. If the pto shaft from the tractor slows and the engine isn't lugging it sounds like a problem to me, but I'm not familiar with hydro's... Good luck!

TCBoomer · Jun 6, 2004

Did the engine lug at the same time? Like Glenn said...try slowing the tractor speed down.

FWIW...part of my lawn has a 25+/- degree slope. A few times while starting out at the bottom, when going uphill, the engine and mower would slow down slightly. I just let up on the pedal and it recovers. 99% of the time it doesn't do it.

Could it be due to thick/wet grass?

Bob

cvpuser · Jun 6, 2004

No, the engine isn't lugging down at all -- it keeps right on humming in the 3000 RPM range. The shaft slows down without any other discernable symptom. If I stop the tractor and raise the cutter, the shaft will spin back up to speed.

The grass isn't wet or very long -- about 7 - 9 inches, and not very thick. On a scale of 1 to 10, with 10 being the longest grass I've cut with this rig, it's about a 4.

Does it sound like a PTO problem?

TCBoomer · Jun 6, 2004

Does it sound like a PTO problem? 

Hate to say it, but it might be /forums/images/graemlins/frown.gif

If your TC40 is a gear model, there is a one way clutch that might be slipping. If it's a HST, I would think you'd have other problems besides just a lazy PTO.

You have the repair manual?

jinman · Jun 6, 2004

The PTO on a Class III Boomer is essentially the same on a gear or HST model. There is a hydraulic clutch and brake that controls the PTO. Right off the top of my head I can't remember for sure, but I think it takes hydraulic pressure to release the brake and engage the clutch. Anyway, if you don't fully engage the PTO lever, the clutch will slip when you hit heavy grass. If your PTO is actually slowing rotation, it's the clutch slipping. If the PTO lever is fully engaged, you have a problem.

Do you slowly engage the PTO or do you just quickly engage it and let the cutter's slip clutch control slippage? There is a chance you have damaged your internal clutch. Even if you have a slip clutch, you should bring your throttle back to near idle before engaging/disengaging the PTO. This will save the extra stress put on the clutch by a 6' or 7' cutter.

I hope it's just your lever not fully engaged or the cutter. Otherwise your tractor may have to be split to repair a worn PTO clutch. /forums/images/graemlins/frown.gif

TCBoomer · Jun 6, 2004

Jim
I thought I read somewhere that gear tractors use a one way roller clutch for the PTO

jinman · Jun 6, 2004

( thought I read somewhere that gear tractors use a one way roller clutch for the PTO )

I'm not sure about all Boomers, but the Class IIIs all use the same clutch. As a matter of fact, there is a pressure adjustment located below the operators seat (seat has to be removed) to adjust the hydraulic pressure that is diverted from the normal tractor hydraulic system. If this pressure is too low and the clutch slips too long, it will wear out early and have to be replaced. If you are lucky, only a pressure adjustment will be needed and the clutch can be saved by careful (low RPM) engagement and disengagement of the PTO. /forums/images/graemlins/cool.gif

cvpuser · Jun 7, 2004

Thanks, Jinman and everyone else who's offered help.

To answer your question, yes, I very slowly engage the PTO with the throttle all the way down. The PTO engagement lever, though, has never traversed the entire length of the guide -- it just won't move that far.

I'm right at the end of my warranty, so I'm going to take it in to the dealer next week to have him give it a good going over before the warranty expires. I'll have him check the PTO thoroughly.

Thanks, everyone. You've confirmed my suspision that the PTO may be in trouble.

jinman · Jun 8, 2004

When my tractor is cold, the PTO starts to engage about 1/2" out of the disengaged detent in the control lever slot. When the tractor warms up, I have to move the lever another 1/4" to start engagement, but my lever will move all the way to the end of the slot.

My point is that the PTO clutch acts differently when the tractor is warm (probably due to hot/thinner hydraulic oil). Your tractor may have a similar effect and the slippage might not show up until the tractor gets warm, especially if the lever is not fully engaged.

Did you buy your tractor from the dealer on Hwy. 121 in Ft. Worth? Just curious... I bought parts for my Ford Jubilee from them, but nothing else.